1. Field of the Invention
The present invention relates to a liquefied gas evaporating device for marine engines.
The invention is intended to supply sea water-cooled boat engines with liquefied petroleum gas, whether they are inboard, outboard or Z-drive four-stroke or two-stroke engines with pressurized lubricating circuit; but it is particularly adapted, however, for engines located within the boat.
2. Discussion of Background Information
Liquefied petroleum gas (LPG) is increasingly used as a source of energy for internal combustion engines. Indeed, this fuel has very interesting advantages, chief among them being very low pollution and an advantageous taxation practiced by numerous countries and allowing a substantial reduction in fuel cost.
Using liquefied gas to operate an engine initially designed to receive a liquid fuel requires a special device ensuring the evaporation of the gas under pressure and with a predetermined throughput.
This device is in the form of a box, generally made of light cast metal such as aluminum and comprising a thermal chamber in which circulates a hot liquid generally constituted by the engine cooling water, the box being arranged so as to enable the liquid to transfer to the gas the thermal energy that is necessary for its evaporation.
For sea water-cooled marine engines, it is difficult, even impossible, to use the cooling liquid to directly provide the heat supply necessary for the evaporation of the liquefied gas, sea water having a corrosive action on the constituent materials of the device, the thermal chamber running the risk of rapidly deteriorating the latter, this corrosive action being further increased by the high temperature of the sea water coming out of the engine.
The inventors of the present invention have filed several patent applications related to the heating of liquefied gas vaporizers adapted particularly to boat engines:
the vaporizer object of the document No. FR 2 757 217 comprises, within the thermal chamber, a container or tubular circuit made of a material which is not subject to the corrosive action of heated sea water, this container or circuit being connected to the cooling water intake or outlet, the thermal chamber being filled with a substance in liquid or paste form which is a good heat conductor capable of transmitting the thermal energy to the evaporation chamber.
The document No. 2 759 419 discloses a vaporizer equipped with a heating element constituted of an electrical resistance connected to the electric circuit of the engine or to an external source.
The International Patent No. WO 98/55 758 describes an evaporation housing whose temperature chamber is branch-connected, by a double conduit, to the engine lubricating circuit.
The Patent Application No. FR 98 08 110 relates to a system comprising a sealed enclosure provided with a heat supply element and connected to the thermal chamber of the liquefied gas evaporating box by a double channel to form a closed circuit in which circulates, due to a pump, a fluid transferring heat from the heated enclosure to the vaporizer.
While these devices solve certain problems posed by the evaporation of liquefied gas, they have a certain number of disadvantages. The first one cited does not allow a good heat transfer between the hot liquid and the evaporating chamber. The use of an electrical resistance arranged in the thermal chamber of the vaporizer makes it difficult to produce a sufficient quantity of energy with a standard evaporating box and, to function properly, requires using an oversized apparatus. The device using the engine lubricating fluid cannot be used for a two-stroke engine and involves risks of leakage from the lubricating system. Finally, the use of a separate enclosure results in a cumbersome and expensive installation.
The device according to the present invention attempts to remedy these disadvantages. Indeed, it makes it possible to obtain vaporizers at a manufacturing cost which is substantially equal to that of the devices used in land vehicles, which can be used under excellent conditions in see water-cooled marine engines and ensure a very good heat exchange between the cooling liquid and the gas to be vaporized.
The invention therefore provides a liquefied gas evaporating box comprising an element in which circulates the water which has been used to cool the engine, this element being made of a sea water resistant material such as brass or bronze and supplied by the engine cooling water by way of a pump located on the exhaust system.
The invention provides a liquefied gas evaporating device for marine engines, making it possible to supply sea water-cooled boat engines with liquefied petroleum gas, whether they are inboard, Z-drive or outboard four-stroke or two-stroke engines with pressurized lubrication circuit. This device is constituted of a box comprising a heating body incorporating an evaporating chamber and a thermal chamber which are contiguous and separated by a common wall, characterized in that the thermal chamber allows therethrough the hot sea water coming out of the cooling circuit of the engine due to an accelerating pump mounted on the evacuation pipe of the cooling circuit, between the engine and the thermal chamber. The heating body is made of a material resisting the corrosive action of the sea water.
The heating body can be made of bronze or brass, and can be identical to that of the known vaporizers made of aluminum casting and made with the tools used for the latter. The heating body can also be made of synthetic resin. The synthetic resin used for manufacturing the heating body can be loaded with metallic particles or fibers so as to improve the thermal conductivity.
The evaporating box can be located on board the boat to supply an outboard engine, with the thermal chamber being connected to the cooling circuit by a single flexible pipe, the discharge going directly into the sea.
The evaporating box can be located on board the boat to supply an outboard engine, with the thermal chamber being connected to the cooling circuit by a double flexible pipe constituting a branch conduit for evacuating the engine cooling water.
The invention also provides for a liquefied gas evaporating device for supplying liquefied petroleum gas to a marine engine, comprising a box that includes a heating body incorporating an evaporating chamber and a thermal chamber which are contiguous and separated by a common wall. The thermal chamber allows therethrough hot sea water coming out of a cooling circuit of an engine via an accelerating pump mounted on an evacuation pipe of said cooling circuit, between said engine and said thermal chamber. The heating body is made of a material that resists corrosive action of sea water.
The marine engine may comprise one of inboard engine, a Z-drive engine, a four-stroke engine, an outboard engine, a two-stroke engine, and an engine with a pressurized lubrication circuit. The heating body may be made of one of bronze and brass. The heating body may be made of an aluminum casting. The heating body may be made of synthetic resin. The synthetic resin may be loaded with one of metallic particles and fibers which can improve a thermal conductivity of the synthetic resin. The heating body may comprise a synthetic resin which includes one of metallic particles and fibers.
The device may be mounted to a boat and coupled to an outboard engine, the thermal chamber may be connected to the cooling circuit by a single flexible pipe, and a discharge may be provided to direct sea water directly into the sea.
The device may be mounted to a boat and coupled to an outboard engine, the thermal chamber may be connected to the cooling circuit by a double flexible pipe that includes a branch conduit for evacuating engine cooling water.
The invention also provides for a system for supplying liquefied petroleum gas to a marine engine, comprising a heating body that includes an evaporating chamber and a thermal chamber. A wall is common to the evaporating chamber and the thermal chamber. The thermal chamber has an inlet which receives hot water from a cooling circuit of an engine and an outlet which discharges the hot water. The evaporating chamber has an inlet which receives gas from a supply reservoir and an outlet which is coupled to the marine engine. A pump is mounted on an evacuation pipe of the cooling circuit, the pump delivering the hot water to the inlet. The heating body is made of a material that resists corrosive action of the hot water.
The marine engine may comprise one of an inboard engine, a Z-drive engine, a four-stroke engine, an outboard engine, a two-stroke engine, and an engine with a pressurized lubrication circuit.
The heating body may be made of one of bronze and brass. The heating body may be made of an aluminum casting. The heating body may be made of synthetic resin. The synthetic resin may be loaded with one of metallic particles and fibers which can improve a thermal conductivity of the synthetic resin. The heating body may comprise a synthetic resin which includes one of metallic particles and fibers.
The invention also provides for a system for supplying liquefied petroleum gas to a marine engine, comprising a heating body that includes an evaporating chamber and a thermal chamber. A wall is common to the evaporating chamber and the thermal chamber. The thermal chamber has an outlet and an inlet which receives marine water. The marine water is taken from a marine environment, heated by the marine engine and delivered to the outlet of the thermal chamber. The evaporating chamber has an inlet which receives gas from a supply reservoir and an outlet which is coupled to the marine engine. A pump delivers the marine water to the inlet of the thermal chamber. A discharge conduit removes the marine water from the outlet of the thermal chamber to the marine environment. The heating body is made of a material that resists corrosive action of the marine water.